The present invention relates to a memory card connector and cover apparatus and method. More particularly, the present invention relates to an improved electrical connector and cover apparatus for a PC card, such as a memory card, which includes an improved electrostatic discharge (ESD) mechanism which also facilitates assembly of the PC card connector and cover.
Conventional memory card holders include a plastic frame for supporting a printed circuit board. Connectors are typically coupled to each end of the frame for providing an electrical connection to the printed circuit board. Metal covers are then placed over the frame to shield and protect the printed circuit board. See, for example, U.S. Pat. No. 5,330,360; U.S. Pat. No. 5,339,222; U.S. Pat. No. 5,386,340; and U.S. Pat. No. 5,476,387.
Another type of PC card does not require the separate plastic frame. In this frameless embodiment, connectors are separately placed on a printed circuit board, using a separate placement step for each connector. The connectors are then soldered to the printed circuit board. The connectors and the printed circuit board are then covered with top and bottom metallic covers.
The apparatus and method of the present invention also does not require use of the separate plastic frame for holding the circuit board. The present invention includes a front end socket having a plastic body portion which houses metallic contacts for engaging conductive pads on the printed circuit board. The apparatus also includes a back end plug which is a plastic shell used to close a rear end of the PC card. If desired, metal contacts can also be inserted into the back end plug to permit electrical signal transfer through the back end plug.
The apparatus of the present invention further includes ESD rails which extend between the front end socket connector and the back end plug. These rails are metal strips that are configured to provide a static electricity drain between the printed circuit board and external metal covers which are coupled to the electrical ground of the system. The ESD rails also couple the front end socket connector to the back end plug to provide a separate subassembly which can be placed as a single unit on the printed circuit board.
The apparatus of the present invention therefore facilitates placement of the connectors on the printed circuit board during assembly of the PC card. The rails provide stability to the connectors during processing and eliminate the requirement of a separate placement operation for both connectors.
Without the rails, the front end connector and the back end plug must be separately placed onto the circuit board during assembly of the PC card. These connectors rest on edges of the printed circuit board which creates a natural tendency for the connectors to move or fall off the printed circuit board if fixturing or adequate board retention is not present. The rails of the present invention change the center of gravity of the connectors once the subassembly is formed to reduce the likelihood that the connectors will fall off the printed circuit board. The rails strengthen and stabilize the PC card.
After the subassembly including the front end connector, the back end plug, and the ESD rails is assembled, placed on the circuit board, and soldered, metal covers are then placed over the subassembly and the circuit board without the requirement of a separate plastic support frame for the printed circuit board.
The improved apparatus and method of the present invention only requires one placement operation to place two connectors on the printed circuit board, without the use of fixturing or retentive devices. A static electricity drain is normally required between the printed circuit board and the ground chassis of the master unit. The present apparatus uses the required static electricity drain as a tie rail between the front end connector and back end plug. This allows for single connector placement at a very little cost increase for the product.
According to one aspect of the present invention, a PC card apparatus includes a printed circuit board having the front end edge, a rear end edge, and first and second side edges. The printed circuit board includes a plurality of conductive pads. The apparatus also includes a front end connector located adjacent the front end edge of the printed circuit board. The front end connector has an insulative body and a plurality of conductive contacts which are coupled to the conductive pads on the printed circuit board. The apparatus further includes a back end plug located adjacent the rear end edge of the printed circuit board, and at least one metal rail having a first end coupled to the front end connector, a second end coupled to the back end plug, and an integral foot section coupled to a ground conductive pad on the printed circuit board to couple the rail to the printed circuit board electrically. The apparatus also includes a conductive cover surrounding the printed circuit board, the front end connector, the back end plug, and the at least one metal rail. The at least one rail is electrically coupled to the conductive cover to provide an electrostatic discharge path between the conductive cover and the printed circuit board.
In the illustrated embodiment, the conductive cover includes a bottom conductive cover coupled to the front end connector and back end plug. The bottom cover is formed to include side edges extending upwardly along the side edges of the printed circuit board. The conductive cover also includes a top conductive cover coupled to the front end connector and back end plug. The top cover is formed to include first and a second channels configured to surround the side edges of the bottom cover to secure the top and bottom covers together. The at least one rail is electrically coupled to the top and bottom conductive covers to provide the electrostatic discharge path.
Also in the illustrated embodiment, the top cover is formed to include at least one front tab configured to enter a slot formed in a top surface of the front end connector and at least one rear tab configured to enter a slot formed in a top surface of the back end plug to couple the top cover to the front end connector and back end plug, respectively. The bottom cover is formed to include at least one front tab configured to enter a slot formed in a bottom surface of the front end connector and at least one rear tab configured to enter a slot formed in a bottom surface of the back end plug to couple the bottom cover to the front end connector and back end plug, respectively.
The illustrated embodiment also includes first and second spaced apart metal rails which are coupled to the front end connector and to the back end plug. The first and second rails are located adjacent the first and second side edges of the printed circuit board, respectively. Each metal rail is formed to include at least one front tab configured to enter a slot formed in the front end connector and at least one rear tab configured to enter a slot formed in the back end plug to couple the rail to the front end connector and back end plug, respectively.
The printed circuit board is formed to include first alignment apertures located near the front end edge and second alignment apertures located near the rear end edge. The front end connector is formed to include alignment pins configured to enter the first alignment apertures, and the back end plug is formed to include alignment pins configured to enter the second alignment apertures to align the front end connector and back end plug, respectively, relative to the printed circuit board. Each rail includes an upwardly extending tab portion configured to engage the conductive cover, and is preferably stamp formed from a sheet metal material.
According to another aspect of the present invention, a method is provided for assembling a PC card apparatus which includes a printed circuit board having a front end edge, a rear end edge, and first and second side edges, the printed circuit board being formed to include a plurality of conductive pads, a front end connector having an insulative body and a plurality of conductive contacts, a back end plug, and a conductive cover. The method includes the steps of providing at least one metal rail, coupling the at least one metal rail to the front end connector and to the back end plug to form a subassembly, and placing the subassembly on the printed circuit board as a single unit with the front end connector located adjacent the front end edge of the printed circuit board and with back end plug located adjacent the rear end edge of the printed circuit board. The method also includes the steps of soldering the contacts of the front end connector to the conductive pads of the printed circuit board, and installing the conductive cover over the printed circuit board, the front end connector, the back end plug, and the at least one metal rail.
In the illustrated method, the step of installing the conductive cover includes the step of coupling a bottom conductive cover to a bottom surface of the front end connector and to a bottom surface of the back end plug, and the step of coupling a top conductive cover to a top surface of the front end connector and to a top surface of the back end plug. The top cover is configured to engage the bottom cover.
The at least one metal rail is configured to engage the conductive cover and is formed to include an integral foot section configured to engage a ground conductive pad on the printed circuit board. The soldering step includes the step of soldering the integral foot section of the at least one metal rail to a ground conductive pad on the printed circuit board to provide an electrostatic discharge path between the conductive cover and the printed circuit board.
In the illustrated method, the coupling step includes the steps of coupling first and second spaced apart metal rails to the front end connector and to the back end plug. The first and second rails are located adjacent the first and second side edges of the printed circuit board, respectively, during the placing step.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.